如何使用 java 将 curl 命令转换为 HTTP POST 请求

Question

I would like to run this specific curl command with a HTTP POST request in java

curl --location --request POST "http://106.51.58.118:5000/compare_faces?face_det=1" \
  --header "user_id: myid" \
  --header "user_key: thekey" \
  --form "img_1=https://cdn.dnaindia.com/sites/default/files/styles/full/public/2018/03/08/658858-577200-katrina-kaif-052217.jpg" \
  --form "img_2=https://cdn.somethinghaute.com/wp-content/uploads/2018/07/katrina-kaif.jpg"

I only know how to make simple POST requests by passing a JSON object, But i've never tried to POST based on the above curl command.

Here is a POST example that I've made based on this curl command:

curl -X POST TheUrl/sendEmail 
-H 'Accept: application/json' -H 'Content-Type: application/json' 
-d '{"emailFrom": "smth@domain.com", "emailTo": 
["smth@gmail.com"], "emailSubject": "Test email", "emailBody":
"708568", "generateQRcode": true}' -k 

Here is how i did it using java

    public void sendEmail(String url) {
        try {
            URL obj = new URL(url);
            HttpURLConnection con = (HttpURLConnection) obj.openConnection();

            //add reuqest header
            con.setRequestMethod("POST");
            con.setRequestProperty("Content-Type", "application/json; utf-8");
            con.setRequestProperty("Accept", "application/json");
            con.setDoOutput(true);

            // Send post request
            JSONObject test = new JSONObject();
            test.put("emailFrom", emailFrom);
            test.put("emailTo", emailTo);
            test.put("emailSubject", emailSubject);
            test.put("emailBody", emailBody);
            test.put("generateQRcode", generateQRcode);
            String jsonInputString = test.toString();
            System.out.println(jsonInputString);
            System.out.println("Email Response:" + returnResponse(con, jsonInputString));
        } catch (Exception e) {
            System.out.println(e);
        }
        System.out.println("Mail sent");
    }

    public String returnResponse(HttpURLConnection con, String jsonInputString) {
        try (OutputStream os = con.getOutputStream()) {
            byte[] input = jsonInputString.getBytes("utf-8");
            os.write(input, 0, input.length);
        } catch (Exception e) {
            System.out.println(e);
        }
        try (BufferedReader br = new BufferedReader(new InputStreamReader(con.getInputStream(), "utf-8"))) {
            StringBuilder response = new StringBuilder();
            String responseLine = null;
            while ((responseLine = br.readLine()) != null) {
                response.append(responseLine.trim());
            }
            return response.toString();
        } catch (Exception e) {
            System.out.println("Couldnt read response from URL");
            System.out.println(e);
            return null;
        }
    }

I've found this useful link but i can't really understand how to use it in my example.

Is it any different from my example? and if yes how can i POST the following data?

Note: Required Data

HEADERS:

user_id myid
user_key mykey

PARAMS:
face_det 1
boxes 120,150,200,250 (this is optional)


BODY:

img_1
multipart/base64 encoded image or remote url of image

img_2
multipart/base64 encoded image or remote url of image

Here is the complete documentation of the API

Answer 1

There are four things that your HttpURLConnection needs:

• The request method. You can set this with setRequestMethod .
• The headers. You can set them with setRequestProperty .
• The content type. The HTML specification requires that an HTTP request containing a form submission have application/x-www-form-urlencoded (or multipart/form-data ) as its body's content type. This is done by setting the Content-Type header using the setRequestProperty method, just like the other headers.
• The body itself needs to URL-encoded, as the content type indicates. The URLEncoder class exists for this purpose.

Those four steps look like this:

String img1 = "https://cdn.dnaindia.com/sites/default/files/styles/full/public/2018/03/08/658858-577200-katrina-kaif-052217.jpg";
String img2 = "https://cdn.somethinghaute.com/wp-content/uploads/2018/07/katrina-kaif.jpg";

con.setRequestMethod("POST");
con.setDoOutput(true);

con.setRequestProperty("user_id", myid);
con.setRequestProperty("user_key", thekey);

con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");

String body = 
    "img_1=" + URLEncoder.encode(img1, "UTF-8") + "&" +
    "img_2=" + URLEncoder.encode(img2, "UTF-8");

try (OutputStream os = con.getOutputStream()) {
    byte[] input = body.getBytes(StandardCharsets.UTF_8);
    os.write(input);
}

You should remove all catch blocks from your code, and amend your method signatures to include throws IOException . You don't want users of your application to think the operation was successful if in fact it failed, right?